1. Technical Field
The present invention relates to a magnet bearing device and a rotor rotary-drive apparatus including the magnet bearing device.
2. Background Art
With rotor unbalance in a magnetic suspension rotor, vibration with a rotational frequency component is caused due to the rotor unbalance, and then, is transmitted to a stator side by electromagnetic force reaction. Patent Literature 1 describes a magnet bearing control device configured to reduce and compensate for the above-described undesirable vibration caused on the stator side.
In the technique described in Patent Literature 1 (JP-A-52-93852), a rotational speed conversion circuit is provided for generation of a rotation angle ωt, calculation being made based on the rotation angle ωt. Generally, examples of the device configured to generate the rotation angle ωt include a Hall sensor and a magnetic position detector (a resolver). The rotation angle ωt is generated from a pulse signal or a sine wave signal of the magnetic pole position detected by the above-described devices.
As described above, in the technique described in Patent Literature 1, the rotation detection device such as the Hall sensor is required for generation of the rotation angle wt.